Our studies together with those of other investigators have established intact absorption for a wide range of dipeptides in the intestine of experimental animal as well as that of man. In addition, our studies have shown that the intact absorption is the major mechanism for the intestinal disappearance of dipeptides. The functional characteristics of the dipeptide carrier system in human intestine have been determined in our laboratory. These studies have shown that: (1) absorption of dipeptides is mediated by a carrier which is not shared with free neutral amino acids; (2) both C- and N- terminal amino acids are influential in imposing the affinity of a dipeptide for the absorption sites.